“metal”的概念、定义、翻译、参考文献-科学参考

metal

Physics

A substance that is a good conductor of heat and electricity. Metals have a number of characteristic properties, such as ductility, malleability, and being shiny. These properties can be understood in terms of the quantum mechanics of electrons in solids, particularly using the concepts of energy bands and the Fermi surface. In particular, the existence of a metal is due to an energy band being unfilled. A metal is sometimes described as being a lattice in a ‘sea’ of electrons. It is the free electrons that are responsible for the good electrical and thermal conduction of metals. In a metal, the atoms are packed together closely, with these atoms being atoms of electropositive elements. Most elements are metals, with mercury being the only element that is a liquid metal at room temperature.

Astronomy

In astronomical terminology, any element heavier than hydrogen or helium. The abundance of such heavy elements in celestial objects is termed their metallicity.

Chemistry

Any of a class of chemical elements that are typically lustrous solids that are good conductors of heat and electricity. Not all metals have all these properties (e.g. mercury is a liquid). In chemistry, metals fall into two distinct types. Those of the s- and p-blocks (e.g. sodium and aluminium) are generally soft silvery reactive elements. They tend to form positive ions and so are described as electropositive. This is contrasted with typical nonmetallic behaviour of forming negative ions. The transition elements (e.g. iron and copper) are harder substances and generally less reactive. They form coordination complexes. All metals have oxides that are basic, although some, such as aluminium, have amphoteric properties. The electrical conductivity of metals occurs because they have at least one unfilled energy band.

Chemical Engineering

One of a number of chemical elements such as nickel, iron, and copper that are characterized as being lustrous ductile solids at room temperature. They form basic oxides, form positive ions, and are good conductors of heat and electricity. An alloy, such as steel, contains one or more of these chemical elements.

Electronics and Electrical Engineering

Any of a class of chemical elements, including copper and iron, that are usually solids and are good conductors of electricity and heat. Alloys, such as brass or steel, containing one or more metals are also considered as metals. The atoms in a metal or alloy crystal are held together by a covalent bond known as metallic bond: a regular lattice of positive ions held together by a cloud of free electrons that move through the lattice. See also energy bands.

单词	metal
释义	metal Physics A substance that is a good conductor of heat and electricity. Metals have a number of characteristic properties, such as ductility, malleability, and being shiny. These properties can be understood in terms of the quantum mechanics of electrons in solids, particularly using the concepts of energy bands and the Fermi surface. In particular, the existence of a metal is due to an energy band being unfilled. A metal is sometimes described as being a lattice in a ‘sea’ of electrons. It is the free electrons that are responsible for the good electrical and thermal conduction of metals. In a metal, the atoms are packed together closely, with these atoms being atoms of electropositive elements. Most elements are metals, with mercury being the only element that is a liquid metal at room temperature. Astronomy In astronomical terminology, any element heavier than hydrogen or helium. The abundance of such heavy elements in celestial objects is termed their metallicity. Chemistry Any of a class of chemical elements that are typically lustrous solids that are good conductors of heat and electricity. Not all metals have all these properties (e.g. mercury is a liquid). In chemistry, metals fall into two distinct types. Those of the s- and p-blocks (e.g. sodium and aluminium) are generally soft silvery reactive elements. They tend to form positive ions and so are described as electropositive. This is contrasted with typical nonmetallic behaviour of forming negative ions. The transition elements (e.g. iron and copper) are harder substances and generally less reactive. They form coordination complexes. All metals have oxides that are basic, although some, such as aluminium, have amphoteric properties. The electrical conductivity of metals occurs because they have at least one unfilled energy band. Chemical Engineering One of a number of chemical elements such as nickel, iron, and copper that are characterized as being lustrous ductile solids at room temperature. They form basic oxides, form positive ions, and are good conductors of heat and electricity. An alloy, such as steel, contains one or more of these chemical elements. Electronics and Electrical Engineering Any of a class of chemical elements, including copper and iron, that are usually solids and are good conductors of electricity and heat. Alloys, such as brass or steel, containing one or more metals are also considered as metals. The atoms in a metal or alloy crystal are held together by a covalent bond known as metallic bond: a regular lattice of positive ions held together by a cloud of free electrons that move through the lattice. See also energy bands.
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